1. Field of the Invention
The present invention relates to a reel unit. More specifically, the present invention relates to a reel unit for a dual bearing reel on which a spool for winding line that is rotated by a handle can be detachably mounted.
2. Background Information
Generally, a dual bearing reel includes a reel unit that is mounted on a fishing rod, a spool that is rotatively mounted on the reel unit, and a handle that serves to rotate the spool. The handle is rotatively mounted on one side of the reel unit, and is connected to the spool via a gear mechanism. The reel unit includes a frame and a pair of side covers. The frame includes a pair of left and right side plates and connection members that connect both of the side plates, and the pair of side covers covers both sides of the frame. An opening through which the spool is capable of passing is provided in the side plate opposite the side plate on which the handle is mounted, and the side cover that covers this side plate is detachably mounted on the side plate in order to make it easy to remove the spool from the opening.
In order to easily attach or detach the side cover with respect to the side plate with this type of dual bearing reel, the side cover is mounted to the side plate by forming a female threaded portion in the inner peripheral side of the opening in the side plate, and a male threaded portion formed on the outer peripheral side of the end of the side cover is screwed therein (see, for example, Japanese Unexamined Patent Publication No. 2000-125721). Here, the side cover can be easily attached and detached by simply rotating the side cover with respect to the side plate.
With this type of dual bearing reel, it has recently been known to form the frame from a magnesium alloy in order to reduce the weight of the dual bearing reel and improve its design. The frame for this type of dual bearing reel is, for example, unitarily formed with side plates and connection members from a magnesium alloy.
With the aforementioned conventional dual bearing reel, the weight of the dual bearing reel can be reduced and the design can be improved because the side plates and the connection members are formed from a magnesium alloy. However, the corrosion resistance of magnesium alloy is weak compared to that of a common metal, and thus an electrodeposition layer is formed by an electrodeposition treatment on the surface of the magnesium alloy in order to improve the corrosion resistance of the surface. If this type of electrodeposition layer is formed on the surface of the female threaded portion that serves to install the male threaded portion of the side cover, the male threaded portion will become stuck in the female threaded portion because the electrodeposition layer has comparatively elastic qualities. Thus, if the male threaded portion is stuck in the female threaded portion, the threaded portions may not properly engage with each other, and the side cover may be coupled to the side plate in an unstable manner.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved reel unit for dual bearing reel that overcomes problems of the prior art. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.